1. Field of the Invention
The present invention relates generally to optical waveguide telecommunications devices utilized in optical telecommunications systems, and particularly to semiconductor laser optical waveguide devices and methods for making such devices.
2. Technical Background
The present invention relates generally to optical waveguide telecommunications devices, semiconductor lasers, and particularly to semiconductor laser optical waveguide telecommunications modules utilized in optical waveguide telecommunications systems and methods of making such semiconductor laser optical waveguide telecommunications modules. Semiconductor lasers are utilized in optical waveguide telecommunications systems to produce photons. Semiconductor laser optical waveguide telecommunications modules can include pump lasers that pump optical waveguide amplifiers and transmitter lasers that transmit modulated optical signals.
Optical signals generated by transmitter lasers are normally transmitted through optical fibers and the optical signals tend to weaken as they travel along the optical fibers. Optical amplifiers which utilize semiconductor lasers provide an economic means of amplifying such weakened optical signals while maintaining the optical nature of the signal. Erbium doped optical fiber amplifiers have become the dominant means of amplifying optical signals in the 1550 nm optical telecommunications window. Such erbium doped optical fiber amplifiers are normally pumped with 980 nm and/or 1480 nm semiconductor pump lasers. With such an amplifier-pump system, electrical energy applied to the 980 nm (1480 nm) semiconductor pump laser produces 980 nm (1480 nm) photons which are coupled through an optical fiber pigtail into the erbium doped optical fiber. The 980 nm and/or 1480 nm pump light excites/energizes the erbium ions in the erbium doped optical fiber so that optical telecommunications signals such as wavelengths centered about 1550 nm are amplified by the excited/energized erbium ions. The optical pumping of optical amplifiers with semiconductor produced photons has become the standard in the optical telecommunications industry, but the ever growing high output requirements of semiconductor pump lasers poses problems for the making of reliable semiconductor lasers modules. It appears that the commercially available maximum reliable output power of 980 nm semiconductor laser pumps may plateau in the 300 mW output power range while the input pump power requirements of optical amplifiers will continue to climb.
Semiconductor lasers have faced reliability problems with the most prevalent being catastrophic optical facet damage of the semiconductor laser. Total failure of semiconductor lasers have been found when the catastrophic optical facet damage level of laser falls below the operating power output of the laser. Additionally in the past it has been found that dark-line defects and facet corrosion have limited the useful life of semiconductor lasers. Many narrow strip emitter lasers failed before 5,000 hours of operation when operated above a high output power of 100 mW. Special attention to the semiconductor laser itself and protective coatings on the semiconductor laser facets (passivation layers) have resulted in some improvement in the reliability of semiconductor lasers. The making of highly reliable high output semiconductor lasers optical waveguide telecommunications modules requires such special attention not only to the semiconductor laser itself but also the other components of the module and how they interact before and during operation of the laser. Such special attention should include the gas, if any, that is incorporated inside the module.